ADU Constructionin Lemon Grove, CA
An ADU in Lemon Grove can reach 1,200 square feet, and ADUs are exempt from the City's half-street dedication and improvement rules. Parking is mostly waived, and a garage conversion needs no replacement spaces. HCD's December 2025 letter found 16 problems in the City's ADU code, so state law sets the floor. Apply in person with hard-copy plans.
Lemon Grove began as citrus country. The City's 1996 General Plan says Robert Allison bought part of Rancho Mission San Diego in 1869, that the first subdivision came in 1892 with 15 to 20 structures and that ten-acre grove homes earned the town the label 'Pasadena of San Diego County' in 1905. After World War II the orchards gave way to single-family streets, and the Census Bureau's 2024 five-year estimates now count 5,776 detached houses, 61.5 percent of the city's 9,391 homes. Those lots are the supply for ADUs: the City's Housing Element, certified by the state in December 2023, sets a goal of 15 ADUs a year, or 120 over its eight-year cycle, and says the Council adopted the ADU ordinance on May 17, 2022.
This page covers the street rule ADUs escape, what the City's handout allows, HCD's December 2025 findings letter, garage conversions, the preapproved plan track, and what the lot itself decides. City pages loaded without trouble for our research, but the official municipal code site refused automated requests, so the code text here comes from a third-party mirror (GoCodebook, text as of October 22, 2026). Confirm every point with Planning. Price ranges and phases are on our ADU construction page.
Lemon Grove Planning and Building Division rules that apply to ADU construction
Where adu construction permits come from in Lemon Grove: City of Lemon Grove Community Development Department, Building Division.
- The City's ADU handout allows ADUs and JADUs in the RL, RLM, RM, RMH, RP and CG zones, with one ADU and one JADU on a single-family lot and, on multifamily lots, up to two detached ADUs plus conversion of non-livable space up to 25 percent of the existing units. An ADU can be up to 1,200 square feet and 100 percent of the main home, owner occupancy is required only for a JADU, and setbacks are four feet on the sides and rear.
- The handout gives detached ADU height as 16 feet (18 feet within half a mile walking distance of a major transit stop or high-quality transit corridor, plus 2 feet to match the main roof pitch) and 25 feet for an attached ADU, allows an ADU in the front setback if there is nowhere else to put it, and says most ADUs are exempt from parking, including those within half a mile of a bus stop or transit station.
- HCD's findings letter to the City dated December 10, 2025 lists 16 findings that the ADU rules in Municipal Code 17.24.060 (updated in 2022) fail to meet state law and asked for a City response by January 9, 2026. Examples: the City's one ADU plus one JADU limit conflicts with Gov. Code 66323 (a converted ADU, a detached ADU and a JADU on one lot), multifamily lots can have up to eight detached ADUs, the 60 day ministerial approval rule is missing, and the 'complementary' architecture and equal-or-better materials standards are subjective. I did not find whether the City has amended its code since.
- The City's ADU page offers 2025 preapproved ADU plans under AB 1332 (Gov. Code 65852.27) with a 30 day approval track, but no changes to a preapproved plan are allowed (no room reconfiguration, window moves or attaching to other structures), and the other reviewing departments can still comment because topography and site conditions differ.
- For an unpermitted ADU or JADU built before January 1, 2020, the City cites AB 2533 (the City may not deny a permit unless correction is needed because the unit is substandard), posts a Lemon Grove Substandard Housing Checklist, and tells owners they may get a confidential third-party code inspection from a licensed contractor before applying.
- Lemon Grove's code says fire sprinklers are not required for an ADU or JADU unless they are required for the primary dwelling, and a garage converted to an ADU does not need its parking replaced (17.24.060); the HCD letter adds that building an ADU cannot trigger sprinklers in the existing home.
- ADUs and JADUs do not require public street dedication or street improvements under Municipal Code 12.10, which matters because other building permits can trigger those requirements at $85,000 and $100,000 in valuation.
- The City's Housing Element (HCD certified December 26, 2023) says the City Council adopted its ADU ordinance on May 17, 2022 and sets a goal of 15 ADUs a year, or 120 over the eight-year cycle.
Sources for these rules
- lemongrove.ca.gov: adu development standards handout
- hcd.ca.gov: lemon grove adu findings 121025
- lemongrove.ca.gov: accesory dwelling units adu
- gocodebook.com: chapter 17.24 district regulations
- gocodebook.com: chapter 12.10 public street dedication and improvements
- lemongrove.ca.gov: lg final 2021 2029 housing element hcd certified dec 2023 cl
Does a Lemon Grove ADU have to pay for street dedication, sidewalks or curbs?
No, and that is a real advantage. Municipal Code 12.10 can require an owner to dedicate half the street right-of-way at $85,000 of permit valuation and to build half-street improvements at $100,000, adjusted yearly from 2026. ADUs and junior ADUs are on the exempt list, along with roofing, decks, patio covers, pools, sheds, garages, carports and solar. The City inherited narrow streets without sidewalks, curbs or gutters when it incorporated in 1977, and the exemption keeps that history out of a backyard unit's budget.
The exemption belongs to the ADU permit. A detached unit priced in the six figures would pass those thresholds if it were an ordinary addition, and the five-year tally adds non-exempt permits on the same property. If an ADU is paired with a main-house addition, ask the Building Division how the two permits are valued, and read our Lemon Grove room addition page first. The City's street rules also write in the 2022 SB 9 lot-split exception and the state ADU laws.
How many ADUs, how big and how tall? What the City's handout allows
The handout allows ADUs and junior ADUs in the RL, RLM, RM, RMH, RP and CG zones. A single-family lot gets one ADU and one JADU, while a multifamily lot may add up to two detached ADUs plus conversion of non-livable space up to 25 percent of the existing units. An ADU can reach 1,200 square feet and 100 percent of the main home's size, side and rear setbacks are four feet, and owner occupancy is required only for a JADU.
Height depends on the type: 16 feet for a detached ADU, 18 feet within half a mile walking distance of a major transit stop or high-quality transit corridor plus 2 feet to match the main roof pitch, and 25 feet for an attached ADU. An ADU may go in the front setback if nowhere else works, and most ADUs are exempt from parking, including those within half a mile of a bus stop or transit station. A lot near the Massachusetts Avenue trolley station may qualify, so ask Planning to confirm the walking distance.
State law sets the floor under all of this: a city may not cap an ADU below 850 square feet, or 1,000 with more than one bedroom, and must allow 800 square feet with four-foot setbacks (Government Code 66314 and 66321).
What did HCD's December 2025 letter say about Lemon Grove's ADU code?
On December 10, 2025 the state Department of Housing and Community Development sent the City a letter listing 16 findings that the ADU rules in Municipal Code 17.24.060, updated in 2022, fail to meet state law, and asked for a City response by January 9, 2026. Examples: the one ADU plus one JADU limit conflicts with Government Code 66323, which lets a lot hold a converted ADU, a detached ADU and a JADU; the 60 day ministerial approval rule is missing; and the 'complementary' architecture and equal-or-better materials standards are subjective.
Here the sources conflict, and we say so. The handout says a multifamily lot can have up to two detached ADUs, while the letter says such lots can have up to eight. We did not find whether the City answered HCD or has amended its code since, so we cannot say which version a plan checker will apply. State law says a local ordinance governs only where it is consistent with the statute, and HCD can find an ordinance noncompliant (Gov. Code 66326).
Our approach: price the project to the state floor, which a city may not go below, then ask Planning at (619) 825-3805 which standard it is applying to your lot today and get the answer in writing before you pay for drawings.
Garage conversion ADU in Lemon Grove: parking, sprinklers and the zone rule
Converting a garage is the cheapest route, and the City's code does not make you replace the parking: 17.24.060 says a garage converted to an ADU needs no replacement spaces, which matches state law. The residential zones still ask two garaged spaces for each home in RL and RLM, so ask Planning to record the release on your zoning clearance. State law also lets a converted ADU and a JADU share a house or garage footprint, with up to 150 square feet added only for entry and exit (Gov. Code 66323).
Sprinklers are the usual worry. The City's code says fire sprinklers are not required for an ADU or JADU unless the main house needs them, and HCD's letter adds that building an ADU cannot trigger sprinklers in the existing home. Setbacks are waived for a conversion of an existing structure, while new construction is held to no more than four feet at the side and rear.
Typical conversion details are a framed infill where the door was, an egress door, a bathroom, smoke and carbon monoxide alarms, energy compliance and a slab that is level and dry. The Building Division's own checklist governs, and it expects hard-copy plan sets at the counter.
Preapproved plans, custom plans or legalizing an unpermitted unit: which path is open?
The City offers 2025 preapproved ADU plans under AB 1332 (Government Code 65852.27) with a 30 day approval track. The catch is rigidity: no room reconfiguration, no window moves and no attaching to other structures, and other reviewing departments can still comment because topography and site conditions differ. For a custom design the state clock is 15 business days to call an application complete and 60 days to act on a complete one, with deemed approval if the agency stays silent (Gov. Code 66317). HCD says the 60 day rule is missing from the City's code, so keep every date in writing.
An older unit built without permits has its own door. For an ADU or JADU built before January 1, 2020, the City cites AB 2533: a permit may not be denied unless correction is needed because the unit is substandard under Health and Safety Code 17920.3. The City posts a Substandard Housing Checklist, and an owner may hire a licensed contractor for a confidential third-party code inspection before applying.
Either path ends at the same counter: in person, hard-copy plans, a zoning clearance, and an applicant who is a licensed contractor, the owner or an authorized agent. The City says each review cycle takes at least 30 days across four departments.
What does the lot decide: clay soil, slopes, Federal Boulevard flooding and utility lines?
The General Plan says nearly all soils, except those in the east Broadway area, are high-clay with high shrink-swell potential, and that geotechnical studies are required for grading. It names steeper slopes south of Federal Boulevard, north and east of Golden Avenue, east of Lawton Drive and Camino de las Palmas and around parts of Lemon Grove Avenue. Grading over 50 cubic yards needs a City Engineer permit. On Federal Boulevard the plan reports serious flooding almost every year, and Chapter 15.50 asks for a floodplain development permit inside FEMA special flood hazard areas.
Utilities are separate paperwork. Trenching, water and sewer laterals, curb cuts and a dumpster in the street need an Engineering encroachment permit, and a sewer connection change involves the Sanitation District Application. Helix Water District serves the city. State law exempts an ADU of 750 square feet or less from impact fees (Gov. Code 66311.5), but utility connection charges are separate, and we did not verify any Lemon Grove fee amount, so none is printed. A new detached ADU must also carry solar panels under the Energy Code, which conversions do not, according to HCD's handbook.
Brush hillsides and fire hazard maps: does a Lemon Grove ADU lot need extra fire work?
Possibly, and the answer depends on a map we could not fully read. CAL FIRE released updated fire hazard severity zone maps for the City on March 24, 2025, and the City's legend shows High and Moderate zones. Ordinance 468, introduced May 6, 2025 to adopt that map, is one we could not confirm was ever adopted. The building code findings cite large brush-covered hillsides and frequent Santa Ana winds, while the 1996 General Plan rated wildland fire risk low in a nearly built-out city. We name no neighborhood as mapped. Ask the Building Division whether your parcel is, and what that adds.
MDG Builders, CSLB #1040337, is the general contractor, not the crew. We draw the unit, file the application, schedule the trades and answer the inspector, and licensed subcontractors pour, frame, wire and plumb it. Before any of them starts, you can ask for a license number and a certificate of insurance.
ADU photos from Lemon Grove and nearby homes
ADU scenes tied to Lemon Grove, from garage conversions and slabs to finished cottages on the city's ranch-house lots. Tap a photo to enlarge it.
What adu construction costs around Lemon Grove
On the ADU construction page, a garage conversion to a studio or one bedroom sits near $100,000 to $200,000, and a new detached unit of 400 to 800 square feet near $200,000 to $400,000. Three sources stand behind those ranges, and none of them is a Lemon Grove quote. A UC Berkeley survey of owners who finished or applied for an ADU in 2018 and 2019 found a Los Angeles County median of $100,000, the Terner Center put Los Angeles at $148,000 in 2020, and Remodeling magazine's 2025 Cost vs. Value report lists a Los Angeles ADU at $178,536 with about 39.9 percent recovered at resale. San Diego County costs may differ, and the median owner-occupied home in Lemon Grove is worth $705,400. Permit, plan check and utility connection charges go on their own lines in a written proposal, and we printed none of the City's amounts. The ADU cost guide explains how the ranges were built, and the ADU versus JADU guide compares the two unit types. For nearby approaches see ADU construction in El Cajon, San Diego, Chula Vista and Los Angeles. A bath for the unit is on the Lemon Grove bathroom page, a larger attached project on the Lemon Grove room addition page, windows on the Lemon Grove window page, and the Lemon Grove area page lists every trade we cover in the city.
| What it covers | Typical range |
|---|---|
| Garage conversion to a studio or one bedroom | $100,000 to $200,000 |
| New detached ADU, 400 to 800 sq ft | $200,000 to $400,000 |
| UC Berkeley survey, Los Angeles County median, 2018 and 2019 projects | $100,000 overall. $90,000 garage. $180,000 detached. |
| Terner Center and Berkeley CCI, 2020 | $148,000 Los Angeles estimate. $167,000 statewide average. |
| Remodeling Cost vs. Value 2025, Los Angeles | $178,536 job cost |
| Electrical and plumbing, Angi Los Angeles, January 2026 | Electrical $2,600 to $7,800. plumbing $3,900 to $10,400. |
| City permit and plan check fees | Not priced here |
Other work we manage in Lemon Grove
Lemon Grove ADU questions, answered
How do I build an ADU in Lemon Grove?
Confirm the lot's zone with Planning at (619) 825-3805, design the unit, then bring a hard-copy application and plan sets to the Building Division counter, since the City takes no online or digital filings. A zoning clearance comes first or with the permit. Preapproved plans offer a 30 day track if you accept them unchanged.
What is the maximum size ADU I can build?
The City's handout allows an ADU of up to 1,200 square feet and up to 100 percent of the main home's size. State law caps a JADU at 500 square feet inside the house and keeps a city from setting an ADU maximum below 850 square feet, or 1,000 with more than one bedroom.
How much does it cost to build an ADU in California?
Expect roughly $100,000 to $200,000 to turn a garage into a studio or one bedroom, and $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. Those ranges lean on Los Angeles area sources, since we found no Lemon Grove survey, and your price comes from a written proposal.
Do I need to provide parking for my ADU?
Usually not. The City's handout says most ADUs are exempt from parking, including those within half a mile of a bus stop or transit station, and the code says a garage converted to an ADU needs no replacement parking. Confirm your lot's status with Planning before you drop a garage space from the plan.
What is the difference between an ADU and a JADU?
An ADU is a complete second home of up to 1,200 square feet that can be detached, attached or converted. A JADU is a unit of up to 500 square feet carved from the main house, with an efficiency kitchen. A single-family lot can hold one of each under the City's handout, and only the JADU triggers owner occupancy.
Do I have to live on the property to build or rent an ADU?
Not for an ADU. The City's handout requires owner occupancy only for a JADU, and state law bars a city from requiring it for an ADU. A city may require that rentals run 30 days or longer. If the unit is a JADU, the City expects the owner to live on the property.
How long does it take to get an ADU permit?
State law gives the City 15 business days to call an application complete and 60 days to act once it is, and a complete application left unanswered is deemed approved. The City's own review page says each cycle takes at least 30 days across four departments and comments restart the clock, so budget for more than one cycle.
Did HCD find Lemon Grove's ADU rules out of line with state law?
Yes, according to HCD's letter of December 10, 2025, which lists 16 findings and asked for a City response by January 9, 2026. We did not find whether the City answered or amended Municipal Code 17.24.060, so state law is the floor for your plans, and Planning can say which rule it applies to your lot.
Tell us about your Lemon Grove ADU plans
Tell us the street, whether you are weighing the garage or the back yard, roughly when the house was built and whether the lot is flat or sloped, and we will plan the first visit around the City's handout and the state floor.